Question 8

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Jambmaths question: 

Find the sum of the first 11 terms of an A.P. with first term 2 and the common difference 3

Option A: 

187

Option B: 

157

Option C: 

197

Option D: 

200

Jamb Maths Solution: 

$\begin{align}  & a=2,\text{ }d=3\text{, }n=11 \\ & {{S}_{n}}=\tfrac{n}{2}[2a+(n-1)d] \\ & {{S}_{11}}=\tfrac{11}{2}[2\times 2+(11-1)3] \\ & {{S}_{11}}=\tfrac{11}{2}[4+30]=187 \\\end{align}$

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